Pneumatic deniering apparatus



Nov. 8, 1966 E. M. BIDDISON, JR 3,283,564

PNEUMATI C DENIERING APPARATUS Filed Dec. 28, 1964 United States Patent O 3,283,564 PNEUMATIC DENIERIN G APPARATUS Elmer Marc Biddison, Jr., Newark, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed Dec. 28, 1964, Ser. No. 421,242 5 Claims. (Cl. 7337.7)

This invention relates generally to the production of filamentary structures and, more particularly, to the detection of variations in the cross-sectional area of a wire, filament, yarn or sliver as it is advanced axially between points in a process installation.

A related device has been described by Barrell and Buxton in the Journal of Scientific Instruments, vol. 26, pages 105 to 108, March 1949. Although operable and indicative of yarn denier variations, such a device suffers from several functional disadvantages, including the difficulty involved in stringup and the requirement of a critical guide arrangement in order to avoid contact with the yarn. Furthermore, because of the shape and arrangement of parts, false indications are obtained due to changes in shape but not area in succeeding lengths or in the amount of air pumped through the device by the yarn.

The object of this invention is to provide a pneumatic deniering apparatus which can be strung up with ease, provides for self-centering of the continuously advancing yarn and is relatively insensitive to yarn velocity.

This worthwhile objective is achieved by providing a support adapted for mounting adjacent the path of travel of an axially advancing yarn. On this support, there is a monitoring head which has an interior chamber defined by a substantially cylindrical side wall and opposed end walls. One of the end walls is dish-shaped with a central segment in proximal parallelism with the other end wall, the latter and the central segment having aligned apertures which facilitate the advance of yarn through the chamber. A source of pressurized fluid is connected to the chamber which also is in communication with a pressure sensor.

Other objectives and advantages will be apparent from the following description of a preferred embodiment wherein reference is made to the accompanying drawing. In the drawing,

FIGURE 1 is a plan view of the deniering apparatus; and

FIG. 2 is a side view of one section of the monitoring head shown in FIG. 1.

The illustrated embodiment includes a regulated air supply shown schematically at 10. Supply is connected by way of a conduit 12 to a monitoring head 14 which also communicates by way of conduit 16 with a pneumatic detector or pressure sensor shown schematically at 187 Head 14 is fabricated in separate halves or sections 20, 22 which mate at line 24 and are afiixed to a holder or support 26 by fasteners 28, 30. Support 26 is made from spring steel and has spaced legs 32, 34 which can be sprung together to thereby spread the jaws 33, 35 within which sections 20, 22 of head 14 are fastened. In this manner, head 14 is opened to facilitate the easy stringup of yarn 36 and returns automatically to the illustrated, closed position upon release of the force previously applied to legs 32, 34.

It is apparent from the illustration of section 20 in FIG. 2 that head 14 has an interior chamber 37 defined by a cylindrical side wall 38, a first end wall 40 and a second end wall 42, which is dish-shaped and has a central segment 44. The inner surface of segment 44 is in proximal parallelism with a corresponding portion of the inner surface of wall 40. Segment 44 and wall 40 are 3,283,564 Patented Nov. 8, 1966 "ice provided with centrally located, aligned apertures 46, 48 which facilitate the advance of yarn 36 through chamber 37. The dish-shaped contour of end wall 42 is such as to present a shallow annular space 47 connecting the outer regions of chamber 37 with apertures 46, 48.

When holder 26 has been positioned adjacent the path of travel for yarn 36, by suitable attachment of mounting pad 50, the apparatus is placed in operation by admitting pressurized air from supply 10. To facilitate stringup, jaws 33, 35 and the mating surfaces of sections 20, 22 are separated temporarily by springing leg 34 toward leg 32. The mating surfaces are normally in a plane which includes line 24 (FIG. 1) and also intersects apertures 46, 48. Air flows radially from chamber 37 inwardly through annular space 47, impinges uniformly on yarn 36 and flows outwardly through apertures 46, 48. Pneumatic detector 18 is connected over conduits 16 and 12 to chamber 37 so as to sense variations in air pressure caused by changes in the cross-sectional area of yarn 36 as it advances through space 47. Detector 18 includes a strain gauge pressure transducer marketed by Statham Instruments, Inc., Los Angeles, California, which provides the input to a coupled electronic amplifier and computing readout mechanism. The latter converts area changes to variations in denier.

The radially inward flow of air through annular space 47 beneath segment 44 and against yarn 36 tends to center the yarn within apertures 46, 48. This tendency has the distinct effect of reducing sensitivity to shape changes not accompanied by changes in the cross-sectional area of yarn 36. The centering action also inhibits yarn contact with the boundary surfaces of apertures 46, 48 and thus reduces abrasion of the yarn, as well as wear on head 14. It permits wider tolerance in alignment of the yarn and not only reduces monitoring noise by being less sensitive to yarn vibrations but also reduces the amount of vibration.

As a related advantage, it has been found that detections of denier variations with the illustrated head are much less sensitive to yarn velocity than those obtained with known pneumatic monitoring heads. This is probably due to the decreased amount of air pumped into chamber 37 by the yarn. In view of the shallow depth of annular space 47, very short length variations in denier can be determined. Furthermore, the head design lends itself to fabrication in sections which can be assembled and mounted in such a way as to permit separation and stringup, even when the yarn is advancing at high speed.

Various pneumatic detectors and amplifiers, e.g., a simple manometer or a Pure Fluid pneumatic computing readout system marketed by Bowles Engineering, Inc., Silver Spring, Maryland, may be used instead of the Statham strain gauge pressure transducer. Where applicable, such detectors may also be connected to an automatic recorder for readout of denier variations and/ or to a process control point. Instead of the illustrated right circular configuration for side wall 38, other cylindrical shapes, e.g., octagonal or slightly elliptical, can be used if the requirement of a uniform, radial flow to annular space 47 is met. In actual practice, sections 20, 22 have been attached to jaws 33, 35 with lock rings and adhesives rather than fasteners 28, 30. It is apparent that other modifications and variations of a similar nature may be made without departing from the spirit of the present invention which is accordingly intended to be limited only by the .scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An apparatus for detecting variations in yarn denier, said apparatus comprising: a support; a monitoring head on'the support, said head having an interior chamber defined by a substantially cylindrical side wall and opposed end walls, one of said end walls being dishshaped with a central flat segment in close proximity to the other end wall, the latter and said segment each being apertnred for the 'aXial advance of yarn through said chamber, said dish-shaped wall being convergent on the other end wall, said flat segment definining a shallow space between it and the other end wall, said shallow space having a height substantially less than the height of said side wall; a source of pressurized fluid; conduit means connecting the source to said chamber; and a pressure sensor in fluid communication with said conduit means.

2. The apparatus of claim 1 wherein said head comprises two sections having mating surfaces and said support is a resilient member having spaced, opposed jaws adapted to clamp the mating surfaces together, each section being fastened to a jaw.

3. A deniering appartus comprising: a support adapted for mounting adjacent the path of travel of an axially advancing yarn; a monitoring head on said support, said head having an interior chamber defined by a substantially cylindical side wall and opposed end walls, one end wall being dish-shaped with a central flat segment in close proximity to a corresponding portion of the other end wall, the latter and said segment having aligned apertures facilitating the advance of said yarn through the chamber, said dish-shaped wall being convergent on the other end wall, said flat segment defining a shallow space between it and the other end wall, said shallow space having a height substantially less than the height of said side wall; a source of pressurized fluid; conduit means a connecting said source to said chamber; and a pressure sensor in fluid communication with said conduit means.

4. The apparatus of claim 3 wherein said head is comprised of two sections having mating surfaces in a plane which intersects said apertures and said support is a resilient member having spaced, opposed jaws adapted to clamp the mating surfaces together, each section being fastened to a jaw.

5. A deniering apparatus comprising a monitoring head having an interior chamber defined by a substantially cylindrical side wall and a pair of end walls, one end wall being dish-shaped with a central flat segment, the other end wall having a plane inner surface in proximal parallelism with said segment, said end walls having aligned apertures adapted for the advance of yarn through said head, said dish-shaped wall being convergent on said plane inner surface, said fiat segment defining a shallow space bet-ween it and said plane inner surface, said shallow space having a height substantially less than the height of said side wall, said chamber being adapted for connection to a source of pressurized fluid.

References Cited by the Examiner UNITED STATES PATENTS 2,843,882 7/1958 Lewis et al 7337.7 X

2,952,262 9/1960 Pocock et a1. 7337.7 X

3,199,339 8/1965 Lipski 7337.7

LOUIS R. PRINCE, Primary Examiner.

DAVID SCHONBERG, Examiner.

F. H. THOMSON, Assisitant Examiner. 

5. A DENIERING APPARATUS COMPRISING A MONITORING HEAD HAVING AN INTERIOR CHAMBER DEFINED BY A SUBSTANTIALLY CYLINDRICAL SIDE WALL AND A PAIR OF END WALLS, ONE END WALL BEING DISH-SHAPED WITH A CENTRAL FLAT SEGMENT, THE OTHER END WALL HAVING A PLANE INNER SURFACE IN PROXIMAL PARALLELISM WITH SAID SEGMENT, SAID END WALLS HAVING ALIGNED APERTURES ADAPTED FOR THE ADVANCE OF YARN THROUGH SAID HEAD, SAID DISH-SHAPED WALL BEING CONVERGENT ON SAID PLANE INNER SURFACE, SAID FLAT SEGMENT DEFINING A SHALLOW SPACE BETWEEN IT AND SAID PLANE INNER SURFACE, SAID SHALLOW SPACE HAVING A HEIGHT SUBSTANTIALLY LESS THAN THE HEIGHT OF SAID SIDE WALL, SAID CHAMBER BEING ADAPTED FOR CONNECTION TO A SOURCE OF PRESSURIZED FLUID. 